This invention relates to corner posts used in the packaging of articles and, particularly, to corner posts applied, e.g., as vertical corner posts such as for insertion into the corners of a straightsided flexible container adapted for cushioning the straight corners and edges of packaged articles along the full height thereof and also adapted to permit the stacking of the packaged articles on each other without damaging the container or the article contained therein, and horizontal corner posts permitting pick up and movement of packed articles by a squeeze truck without sideways crushing of the articles.
In packaging a number of articles including heavy articles such as refrigerators, television sets, stoves, air conditioners, and washing machines and dryers, it is customary to package them in relatively lightweight containers formed of paperboard or corrugated or to envelop them in a plastic film such as by shrink or stretch wrap techniques. The article is located and cushioned within the container or film by corner posts which typically are one or more pieces of cardboard folded to a 90.degree. angle and inserted along the edges of the article and the corners of the containers or film. Such corner posts are used to provide cushioning to protect the corners of the packed article from damage such as scratching and denting during shipping and handling.
A number of corner posts are known to the art. Representative of such designs are U.S. Pat. Nos. 2,068,771; 2,160,221; 2,196,157; 2,514,833; 3,556,529; 3,133,687; 3,337,111; 3,536,245; 3,072,313; 3,433,354; 3,708,101; 3,734,389; 4,120,441; and G.B. No. 2,080,767. These prior art corner posts, however, all have one or more of the following disadvantages. Although some provide relatively good cushioning, they do not provide a load bearing capacity in the vertical direction which would permit the vertical stacking of loaded containers, or, if they do, they are of substantial bulk and thus require large amounts of materials, are heavy, and take up space. For protectors not providing vertical load bearing capacity, when stacking of such containers is attempted, the weight of the upper container crushes the underlying containers by bending or buckling the walls of the container which bear the stacking load. Others which attempt to provide such vertical load bearing capacity in turn do not always provide sufficient cushioning and/or are relatively complex in design and expensive to manufacture. Since the packaging materials do not add value to the product itself, the costs of such materials are an important consideration to the manufacturer who uses such posts in shipping finished goods. Finally, some designs are subject to crushing by lateral forces supplied to the container and by shifting movement of the article within the container detracting from the cushioning protection for the edge and corners of the article.
In my U. S. Pat. No. 4,771,893, I provide an integral, elongated corner post for cushioning and protecting the edges of a packaged article which provides excellent vertical load bearing or stacking strength and excellent horizontal load bearing strength as the case may be, good cushioning, good impact resistance, substantial thickness for spacing the outer surface of the packaged article from the side walls of the container or film but with a minimum of material, and which is lightweight, clean with no rough edges, and simple in design and relatively economical to produce.
In one preferred form of that invention, the corner post includes a core formed of single-face corrugated having a smooth facing sheet and a corrugated or fluted sheet glued thereto. A second sheet of single-face corrugated is wrapped about this core at least one time with the flutes thereof being adhered to the surfaces of the underlying core and lying perpendicular to the flutes of the core. This wrapping includes the vertical edges of the core giving the corner protector desired smooth, rounded edges. Moreover, the corner protector's outer surface comprises the plain paper face of the second singleface corrugated giving the product a desired continuous, smooth outer surface. The core is scored to permit its bending to a 90.degree. angle; and, when bent, the apex of the angle is smooth and rounded. The perpendicularity of the three layers of flutes and the rounded edges and apex provided the corner post with excellent load bearing strength and minimum warp.
Also known to the art is a corner post comprised of multiple layers of elongated corrugated paper which are bent into right angles laid one upon the other and glued together with the flutes of the corrugated paper extending generally perpendicular to the long direction of the legs. This corner post has, however, relatively poor columnar and beam strength.